PROVINCETOWN — Viewed from the outside, Sutton Foster’s career is the stuff of showbiz lore.

Plucked from the ensemble of “Thoroughly Modern Millie’’ a decade ago to take over the title role, she proceeded to win a Tony Award, delivered a string of acclaimed performances in other Broadway musicals (“The Drowsy Chaperone,’’ “Young Frankenstein,’’ “Shrek the Musical’’), won another Tony (for “Anything Goes’’), and landed the leading part on a well-regarded TV show (“Bunheads’’).

But when Foster tells her own story, as she did last week at the Art House here during an onstage conversation with Seth Rudetsky, the sparkling saga yields to reality — and that turns out be the tale of a performer who has had to battle self-doubt.

That’s not to say that her appearance — part of the summertime treat known as the Broadway @ The Art House series, a combination of cabaret performances and chatty interviews that is hosted by Rudetsky — was a downer. Quite the opposite.

Foster came across as likable, unpretentious, and frequently funny. She yodeled during her performance of “Roll in the Hay,’’ from the 2007 musical version of “Young Frankenstein,’’ where she played Inga, the lab assistant. She acknowledged that she always sings the title tune from “Oklahoma!’’ during auditions, a quirky choice that baffles directors, given that it’s an ensemble number (in a witty touch, she later sang it as her encore). She joked about her height, describing herself as “Giant Eponine’’ in a production of “Les Misérables’’ early in her career and walking stiff-armed, Frankenstein’s-monster-style, to demonstrate. After describing Carol Burnett as one of her idols, she burst into a Burnett-like bit of clowning during a duet with Rudetsky on “Summer Nights,’’ from “Grease.’’

SUTTON FOSTER

The Art House,
Provincetown

Date of first performance:

Friday night

But it was Foster’s matter-of-fact openness about her insecurities that was the most striking part of the 80-minute show, because it opened a window onto the fears that can bedevil even gargantuan talents in the unforgiving arena of Broadway, where a lot of money is riding on each production, along with the reputations of headliners such as Foster.

For instance, very shortly before “Anything Goes’’ opened in 2011, Foster experienced a severe crisis of confidence. “I was pretty convinced I was going to fail,’’ she said, adding: “I was so afraid.’’ Surprising words for anyone who saw her dynamic portrayal of the brassy, indomitable nightclub singer Reno Sweeney — a performance that prompted New York Times critic Ben Brantley to write in his review that Foster’s “triple mastery of words, music, and moves is unmatched by any performer on Broadway at the moment.’’

Yet Foster, who had initially been eager to play Reno, began to feel she wasn’t right for the part as opening night approached. She was daunted by the responsibility of carrying a show and by the thought of the legends who had preceded her as Reno: Ethel Merman, who originated the role, and Patti LuPone, one of Foster’s idols, who played Reno in a 1987 revival. Fundamentally, she told Rudetsky, she just didn’t feel she had captured the character, in part because Reno Sweeney was so utterly different from her. It took an acting coach to help Foster get over her qualms and get her confidence to where it needed to be.

She had enjoyed remarkably early success, landing a role in a national touring production of “The Will Rogers Follies’’ while still a high school student in Michigan. “I had to ask my principal if I could go,’’ Foster said. “I was a child!’’ Other cast members saw the eager young Foster as a threat — she watched them perform from the wings, intent on soaking up whatever she could — and she became “sort of a target.’’ After that experience, she said, “I was kind of beaten down and defeated. I was like ‘Maybe I’m not cut out for this.’ ”

But of course she was. Underscoring her success in conquering her doubts, early and late, Foster delivered bravura renditions at the Art House of several songs from “Anything Goes’’: the title tune, “I Get a Kick Out of You,’’ and “You’re the Top,’’ in a duet with Rudetsky, the two of them trading banter at his white piano.

Her vocal range was on full display in “On My Own,’’ from “Les Misérables’’; when she reached the line “All my life I’ve only been pretending,’’ Foster sent the word “pretending’’ soaring into the empyrean. She brought a pensive and open-hearted quality to Stephen Sondheim’s “Being Alive,’’ from “Company,’’ stretching the song’s final two words — “being alive’’ — to a glorious, life-affirming length.

Her love of musical theater shone through, but so did a clear sense of what a roller coaster ride that career choice can be. “This is horrible!’’ she exclaimed after describing one bout of show-related anxiety. “It’s turning into a therapy session.’’